ios - UITableViewCell 中的 UIButton 被重用

Question

我的表格 View 显示播客数据。所有单元格都可以很好地重复使用，并以正确的顺序显示播客。我将下载和播放按钮添加为每个单元格的 subview 。当我向下滚动列表时，将显示用于隐藏未下载剧集的播放按钮，并将保存先前启动下载的单元格的数据。例如，如果我点击单元格 1 中的下载按钮，它将下载正确的剧集，播放按钮将完美播放该剧集。如果我向下滚动到单元格 10，将出现相同的播放按钮并从按钮 1 播放剧集。我的代码有什么问题？

override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath, object: PFObject?) -> PFTableViewCell? {
    let cell: PFTableViewCell = tableView.dequeueReusableCellWithIdentifier("Cell", forIndexPath: indexPath) as! PFTableViewCell
    if let title = object?["title"] as? String {
        cell.textLabel?.text = title
        let downloadButton = UIButton(type: UIButtonType.Custom)
        downloadButton.frame = CGRectMake(cell.contentView.bounds.width - 100, cell.contentView.bounds.height / 2, 100, 35)
        downloadButton.setTitle("Download", forState: .Normal)
        downloadButton.setTitleColor(UIColor.blueColor(), forState: .Normal)
        downloadButton.tag = indexPath.row
        downloadButton.addTarget(self, action: "downloadEpisode:", forControlEvents: .TouchUpInside)
        cell.addSubview(downloadButton)
        let playButton = UIButton(type: UIButtonType.Custom)
        playButton.frame = CGRectMake(cell.contentView.bounds.width - 100, cell.contentView.bounds.height - 89, 100, 35)
        playButton.setTitle("Play", forState: .Normal)
        playButton.setTitleColor(UIColor.blueColor(), forState: .Normal)
        playButton.tag = indexPath.row
        playButton.addTarget(self, action: "playEpisode:", forControlEvents: .TouchUpInside)
        if let isDownloaded = object?["isDownloaded"] as? String {
            if isDownloaded == "yes" {
                playButton.hidden = false
            } else {
                playButton.hidden = true
            }
        }
        cell.addSubview(playButton)
    }
    return cell
}

编辑:

我也试过这个但它不起作用并且仍然为每个单元格创建 1 个按钮:

     override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath, object: PFObject?) -> PFTableViewCell? {
    let cell: PFTableViewCell = tableView.dequeueReusableCellWithIdentifier("Cell", forIndexPath: indexPath) as! PFTableViewCell
    if let title = object?["title"] as? String {
        cell.textLabel?.text = title
    }
        if let button = cell.viewWithTag(indexPath.row) {
            print(button)
        } else {
            if let isDownloaded = object?["isDownloaded"] as? String {
                if isDownloaded == "yes" {
                    let downloadButton = UIButton(type: UIButtonType.Custom)
                    downloadButton.frame = CGRectMake(cell.contentView.bounds.width - 100, cell.contentView.bounds.height / 2, 100, 35)
                    downloadButton.setTitle("Play", forState: .Normal)
                    downloadButton.setTitleColor(UIColor.blueColor(), forState: .Normal)
                    downloadButton.tag = indexPath.row
                    downloadButton.addTarget(self, action: "playEpisode:", forControlEvents: .TouchUpInside)
                    cell.addSubview(downloadButton)
                } else {
                    let downloadButton = UIButton(type: UIButtonType.Custom)
                    downloadButton.frame = CGRectMake(cell.contentView.bounds.width - 100, cell.contentView.bounds.height / 2, 100, 35)
                    downloadButton.setTitle("Download", forState: .Normal)
                    downloadButton.setTitleColor(UIColor.blueColor(), forState: .Normal)
                    downloadButton.tag = indexPath.row
                    downloadButton.addTarget(self, action: "downloadEpisode:", forControlEvents: .TouchUpInside)
                    cell.addSubview(downloadButton)
                }
            }
    }

    return cell
}

编辑2:

新增下载方式:

        func downloadEpisode(sender: UIButton) {
    print("Downloading..")
    let indexPath = NSIndexPath(forRow: sender.tag, inSection: 0)

    let object = self.objectAtIndexPath(indexPath)
    if let result = object {
    let urlstring = result["downloadURL"] as? String
    if urlstring != nil {
    let episodeURL = NSURL(string: urlstring!)
        downloader.downloadPodcastEpisode(episodeURL!, podcast: result)
        }
    }
}

回答:

尽管所有答案都是正确的，但我最终还是决定删除手机点击上的下载/播放按钮。非常感谢!

Answer 1

问题是您每次都添加一个新 按钮。当您的单元格被重复使用时，它已经有了一个按钮。您需要编写代码来保证按钮只会创建一次，然后修改现有按钮而不是创建新按钮。

有两种常见的方法:

• 使用 viewWithTag 检查按钮是否存在(创建一个按钮，如果不存在则设置其标签)
• 子类 UITableViewCell，在初始化程序中创建按钮，并在每次使用单元格时配置按钮。

搜索“uitableviewcell viewwithtag”或“subclass uitableviewcell”应该会为您提供大量示例代码，因此我不会在这里重复。